Reproduction steps:
1. Open customer's attached project in "CustomRenderBug.zip"
2. Open Scene named "Scene.unity"
3. Notice that there are 2 Quads in the Scene
4. Notice that the blue Quad is using a transparent material with Alpha channel that is semi-transparent (Alpha 145 out of 255)
5. Move around in the Scene so you can see blue Quad overlapping with red one (Blue in front)

Expected result: you will be able to see the red Quad trough the blue Quad because the blue Quad is transparent
Actual result: the blue Quad is rendered as Opaque and nothing can be seen through it (images of Actual and Expected are attached)

Reproducible with: URP 7.4.1 (2019.4.8f1), URP 9.0.0-preview.35 (2020.1.2f1), URP 10.0.0-preview.26 (2020.2.0a20)
Not reproducible with: 7.2.0 (2019.3.6f1), URP 7.3.1 (2019.4.8f1)
Could not test with 2018.4 because couldn't resolve package errors